<script lang="ts" setup name="XtxCarousel">
import { BannerItem } from '@/types/data'
import { onMounted, onUnmounted, ref } from 'vue';
// 一定要写点东西, name 才会生效, 否则没有 name 属性
const { slides, duration = 3000, autoplay = true } = defineProps<{
  slides: BannerItem[],
  duration?: number,
  autoplay?: boolean
}>()

// 定义变量控制小圆点高亮
const active = ref(0)

// 上一张事件
const prev = () => {
  active.value --
  if (active.value < 0) active.value = slides.length - 1
}

// 下一张事件
const next = () => {
  active.value ++
  if (active.value > slides.length - 1) active.value = 0
}

let timerId: null | number = null
const start = () => {
  // 更严谨的处理
  if (!autoplay) return
  // 自动滚动 (页面卸载时能清除)
  // 直接写认为是 Node 的方法, 需要 window. 才对
  timerId = window.setInterval(() => {
    // console.log('自动播放中...')
    next()
  }, duration)
}
const stop = () => {
  // 短路与: 如果前面为 true 才会执行后面的代码
  timerId && clearInterval(timerId)
}

// 页面加载就让定时器开始执行
onMounted(() => start())

// 页面销毁时清除定时器
onUnmounted(() => stop())
</script>

<template>
  <div class="xtx-carousel" @mouseenter="stop" @mouseleave="start">
    <ul class="carousel-body">
      <li v-for="(item, index) in slides" :key="item.id" class="carousel-item" :class="{ fade: active === index }">
        <RouterLink to="/">
          <img
            :src="item.imgUrl"
            alt=""
          />
        </RouterLink>
      </li>
    </ul>
    <a @click="prev" href="javascript:;" class="carousel-btn prev"
      ><i class="iconfont icon-angle-left"></i
    ></a>
    <a @click="next" href="javascript:;" class="carousel-btn next"
      ><i class="iconfont icon-angle-right"></i
    ></a>
    <div class="carousel-indicator">
      <span 
        v-for="(item, index) in slides" 
        :key="item.id" 
        :class="{ active: active === index }"
        @mouseenter="active = index"></span>
    </div>
  </div>
</template>

<style scoped lang="less">
.xtx-carousel {
  width: 100%;
  height: 100%;
  min-width: 300px;
  min-height: 150px;
  position: relative;
  .carousel {
    &-body {
      width: 100%;
      height: 100%;
    }
    &-item {
      width: 100%;
      height: 100%;
      position: absolute;
      left: 0;
      top: 0;
      opacity: 0;
      transition: opacity 0.5s linear;
      &.fade {
        opacity: 1;
        z-index: 1;
      }
      img {
        width: 100%;
        height: 100%;
      }
    }
    &-indicator {
      position: absolute;
      left: 0;
      bottom: 20px;
      z-index: 2;
      width: 100%;
      text-align: center;
      span {
        display: inline-block;
        width: 12px;
        height: 12px;
        background: rgba(0, 0, 0, 0.2);
        border-radius: 50%;
        cursor: pointer;
        ~ span {
          margin-left: 12px;
        }
        &.active {
          background: #fff;
        }
      }
    }
    &-btn {
      width: 44px;
      height: 44px;
      background: rgba(0, 0, 0, 0.2);
      color: #fff;
      border-radius: 50%;
      position: absolute;
      top: 228px;
      z-index: 2;
      text-align: center;
      line-height: 44px;
      opacity: 0;
      transition: all 0.5s;
      &.prev {
        left: 20px;
      }
      &.next {
        right: 20px;
      }
    }
  }
  &:hover {
    .carousel-btn {
      opacity: 1;
    }
  }
}
</style>